Thank you for your query.
It is very normal for the head and body to be warmer than the peripheries (arms and legs) as vital organs are present there and are being constantly perfused with blood. You need to worry only if the there is fever
which can be measured by the thermometer.
If the rash
has disappeared then you need not worry about it. I will not worry about the blotching that you mention.
I hope I have answered your query to your satisfaction.
Wishing your son all the best.
Rajiv K Khandelwal